/*
 * Copyright 2000-2009 JetBrains s.r.o.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.intellij.util.containers.hash;


import org.jetbrains.annotations.NotNull;

import java.util.Arrays;


class HashUtil {
  static final int MIN_CAPACITY = 5;

  static final float DEFAULT_LOAD_FACTOR = 1;

  static final float CAPACITY_MULTIPLE = 1.618033989f;


  public static int hash(Object key) {

    return key == null ? 0 : key.hashCode() & 0x7fffffff;
  }

  public static <K> int hash(K key, @NotNull EqualityPolicy<? super K> hashingStrategy) {
    return key == null ? 0 : hashingStrategy.getHashCode(key) & 0x7fffffff;
  }


  static int adjustTableSize(int size) {

    int i = Arrays.binarySearch(tableSizes, size);

    if (i < 0) {

      i = ~i;
    }

    return tableSizes[i];
  }


  private static final int[] tableSizes = {


    // include all odd primes under 1000

    3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67,

    71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139,

    149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223,

    227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293,

    307, 311, 313, 317, 331, 337, 347, 349, 353, 359, 367, 373, 379, 383,

    389, 397, 401, 409, 419, 421, 431, 433, 439, 443, 449, 457, 461, 463,

    467, 479, 487, 491, 499, 503, 509, 521, 523, 541, 547, 557, 563, 569,

    571, 577, 587, 593, 599, 601, 607, 613, 617, 619, 631, 641, 643, 647,

    653, 659, 661, 673, 677, 683, 691, 701, 709, 719, 727, 733, 739, 743,

    751, 757, 761, 769, 773, 787, 797, 809, 811, 821, 823, 827, 829, 839,

    853, 857, 859, 863, 877, 881, 883, 887, 907, 911, 919, 929, 937, 941,

    947, 953, 967, 971, 977, 983, 991, 997,


    1031, 2063, 4127, 8263, 16529, 33071, 66161, 132329, 264659, 529327, 1058657, 2117317, 4234651, 8469319,

    1091, 2203, 4409, 8819, 17657, 35317, 70639, 141283, 282571, 565163, 1130351, 2260717, 4521509, 9043033,

    1153, 2309, 4621, 9257, 18517, 37039, 74093, 148193, 296437, 592877, 1185787, 2371609, 4743223, 9486469,

    1217, 2437, 4877, 9767, 19541, 39089, 78179, 156361, 312727, 625477, 1250969, 2501953, 5003909, 10007819,

    1283, 2579, 5167, 10337, 20681, 41381, 82763, 165527, 331063, 662141, 1324313, 2648629, 5297287, 10594583,

    1361, 2729, 5471, 10949, 21911, 43853, 87719, 175447, 350899, 701819, 1403641, 2807303, 5614657, 11229331,

    1409, 2819, 5639, 11279, 22567, 45137, 90281, 180563, 361159, 722321, 1444649, 2889317, 5778649, 11557303,

    1481, 2963, 5927, 11863, 23741, 47491, 94993, 189989, 379979, 759959, 1519939, 3039917, 6079861, 12159731,

    1543, 3089, 6197, 12401, 24809, 49627, 99257, 198529, 397063, 794137, 1588289, 3176597, 6353213, 12706451,

    1601, 3203, 6421, 12853, 25717, 51437, 102877, 205759, 411527, 823117, 1646237, 3292489, 6584983, 13169977,

    1667, 3343, 6689, 13381, 26777, 53569, 107171, 214351, 428731, 857471, 1714957, 3429961, 6859933, 13719869,

    1733, 3467, 6947, 13901, 27803, 55609, 111227, 222461, 444929, 889871, 1779761, 3559537, 7119103, 14238221,

    1801, 3607, 7219, 14447, 28901, 57803, 115613, 231241, 462491, 924997, 1850021, 3700043, 7400123, 14800271,

    1861, 3727, 7457, 14923, 29851, 59707, 119417, 238837, 477677, 955363, 1910729, 3821483, 7643017, 15286079,

    1931, 3863, 7727, 15461, 30931, 61871, 123757, 247519, 495041, 990137, 1980281, 3960581, 7921169,

    1993, 3989, 7993, 15991, 31991, 63997, 127997, 256019, 512047, 1024099, 2048203, 4096427, 8192867,


    26339969, 52679969, 105359939, 210719881, 421439783, 842879579, 1685759167,

    28977863, 57955739, 115911563, 231823147, 463646329, 927292699, 1854585413,

    31322867, 62645741, 125291483, 250582987, 501165979, 1002331963, 2004663929,

    17135863, 34271747, 68543509, 137087021, 274174111, 548348231, 1096696463,

    18366923, 36733847, 73467739, 146935499, 293871013, 587742049, 1175484103,

    19845871, 39691759, 79383533, 158767069, 317534141, 635068283, 1270136683,

    21006137, 42012281, 84024581, 168049163, 336098327, 672196673, 1344393353,

    22458671, 44917381, 89834777, 179669557, 359339171, 718678369, 1437356741,

    23723597, 47447201, 94894427, 189788857, 379577741, 759155483, 1518310967,

    25002389, 50004791, 100009607, 200019221, 400038451, 800076929, 1600153859,


    Integer.MAX_VALUE,
  };

  static {

    Arrays.sort(tableSizes);
  }
}

